Method for making a reinforced structural member



Jan. 6, 1970 H. HOPFELD 3,487,518

METHOD FOR MAK- ING A REINFORCED STRUCTURAL MEMBER 2 Sheets-Sheet 1 Original Filed Aug. 12, 1965 ArrokA/EY H. HOPFELD METHOD FOR MAKING A REINFORCED STRUCTURAL MEMBER Jan. 6, 1970 2 Sheets-Sheet 2 Original Filed Aug. 12, 1965 R mm w ww 4r halve-r United States Patent 3,487,518 METHOD FOR MAKING A REINFORCED STRUCTURAL MEMBER Henry Hopfeld, 51 Winship Ave., Ross, Calif. 94957 Original application Aug. 12, 1965, Ser. No. 479,120, now Patent No. 3,349,537, dated Oct. 31, 1967. Divided and this application Aug. 21, 1967, Ser. No. 661,917

Int. Cl. B23p 17/00 U.S. Cl. 29-155 6 Claims ABSTRACT OF THE DISCLOSURE In the methodof making reinforced structural mem-- ber, such as an I beam, the steps of forming each flange into a recess by having its outer edges bent at right angles and then bent inwardly toward one another to form cover walls for a longitudinal pocket along the flange; filling the said pocket or recess above the bottom with strands of glass fiber and suitable binder so that the glass fiber is oriented longitudinally with respect to the flange in such quantity that fiber glass and binder is compressed when the cover walls are pressed in toward one another and inwardly of the recess, then setting the binder to integrate the glass fiber strands with the walls of the recess on the flange.

This is a divisional application of the application of Henry Hopfeld, Ser. No. 479,120, filed Aug. 12, 1965 now Patent No. 3,349,537 granted Oct. 31, 1967 for Reinforced Structural Member.

BRIEF DESCRIPTION OF THE INVENTION For reinforcing in a light material, structural members, such as I beams, which have a flange, with longitudinal strands capable of integral union with the flange, the flange is formed with a bottom and pair of side walls from which are bent cover walls which are also compression walls, and then the space above the bottom and between the side walls is filled with fiber glass and binder oriented longitudinally of the flange, then the cover walls are pressed over and into the filler so as to compact it into the recess gradually and progressively along the structural member, and finally treating the structural member to set the filler and binder for said integral union into the recess.

DESCRIPTION OF FIGURES FIG. 1 is a perspective view of the I beam showing the flanges in open position.

FIG. 2 is a perspective view of the I beam showing the flanges in closed position.

FIG. 3 is an enlarged fragmental perspective view with the flange partly broken way, exposing a glass fiber reinforcement.

FIG. 4 is a perspective view of modified form of flange on the I beam open.

FIG. 5 shows the modified flange structure closed.

FIG. 6 is a perspective fragmental view on an enlarged scale showing a modified flange partly broken away and exposing the reinforcing glass fibers.

FIG. 7 is a perspective view of the I beam with spaced longitudinal recesses in its flanges for enclosing the glass fiber reinforcement.

DETAILED DESCRIPTION Generally the method of reinforcing structural members includes the steps of forming one or more recesses of the structural gnem'ber, filling the longitudinal recess with glass fiber such as so-called fiber glass roving, longitudinally oriented in the recess, providing a binder for the glass fiber, then comp-acting the longitudinally oriented glass fiber and binder by closing the initially open recess upon and around the filler, and finally treating the filler so as to set the same, for instance by subjecting it to heat.

In the specific form herein illustrated on an I beam, such as the side rails or bars of an aluminum ladder, the method includes the steps of forming the flanges of the I beam with hollow longitudinal recesses, corrugating the inner surfaces of the recesses longitudinally, filling the recesses with so-called fiber glass roving oriented 1ongitudinally in the recesses so that the fiber glass strands are parallel with the longitudinal axis of the beam, providing binder for the fiber glass roving in the recess, closing the recess on said filler so as to compact the filler in the recess, then treating the filler for setting and integrating the filler with the respective materials of the recess, for instance by subjecting the flanges to heat and pressure.

In the form shown in FIG. 1, the structural member is an I beam utilized for ladders or similar use where flexural strength is required with minimum side sway, and where lightness is -also.desirable.

The I beam 1, shown in FIGS. 1 to 3, has a longitudinal hollow flange 2 along each edge thereof. The flanges 2 extend to opposite sides of the I beam 1. Each flange 2 is hollow so as to form an initially open longitudinal recess 3. The recess 3 is formed by opposite side walls 4 extended perpendicularly from each edge of the flange 2 away from and parallel with the I beam 1. From the outer edge 5 of each side wall 4 extends a cover plate or flap 6 foldable around the edge 5 inwardly. Each cover plate or flap 6 covers about a longitudinal half of the recess 3. On the free edge of each cover plate 6 is provided a longitudinal hook flange 7 which projects inwardly of the recess 3 when the cover plates 6 are folded together.

The inner faces of the flanges 2, the side walls 4 and the cover plates or flaps 6 have longitudinal corrugations or serrations 8 thereon. In the initial position the cover plates 6 extend away from the adjacent flange 2 so as to leave a longitudinal access opening into the recess 3.

Glass fibers such as fiber glass roving 9 are laid into the recess 3 as shown in FIG. 2. This roving 9 is coated with a suitable binder or if needed, suitable binder is packed in with the roving 9 tightly so as to fill the recess 3 and bulge over under the open cover plates 6. When the cover plates 6 are folded togethe r from the position shown in FIG. 1 into the positions shown in FIGS. 2 and 3, fiber glass roving filler is compacted.

As shown in FIG. 2, the cover plates 6 are folded into the recess 3 by suitable rollers 11, engaging simultaneously the cover plates 6 on both flanges of the I beam 1. As the I beam 1 is passed between the rollers 11 and after the cover plates 6 are folded tightly, heat is applied to the flanges and the cover plates 6 for setting the binder and the fiber glass so as to integrate the filler with the serrated walls of the recess 3.

The form shown in FIG. 4 and FIG. 6 differs from the first described form by providing a shoulder 13 on the top of each side Wall 4, and each cover plate 14 is somewhat larger than the distance between the inner edge 15 of the shoulder 13 and the center plane of the I beam so that when the cover plates 14 are folded about the edges 15, they remain in an inclined position bulging outwardly as shown in FIG. 5 and FIG. 6. In this form also the base flange 16 is formed on a radius on each side of the I beam thereby to increase the space for the filler.

In the form shown in FIG. 7 each flange 21 of the I beam 22 has a plurality of parallel recesses 23 therein. The sides of the recesses have cover projections 24 extended beyond the outside faces 25 of the respective flanges 21. Then fiber glass roving 26 is laid into the recesses 23 together with suitable binder. Then the cover projections 24 are folded'over the filler by rollers'or the like so as to compact and cover the fiber glass roving 26. Then by submitting the flanges to heat treatment while the filler is under compression, the longitudinally oriented glass fiber filler is integrated with the respective flanges.

The product of the method is an I beam which has fiexural strength much greater than the metal with which they are integrated. For instance, in aluminum ladders the flexural strength of the ladder is increased greatly and side-sway is materially reduced, yet the Weight of the ladder is not materially increased.

The integration of this filler with the metal of the flanges results in a pre-stressing of the longitudinal flanges. This pre-stressing is accomplished by rolling down the cover plates or flaps 6 or 14, or the cover projections 24, progressively step by step along the length of the flanges of the structural member thereby. gradually and progressively compressing the strands of fiberglass into the recess and simultaneously curing the binder such as polyester or the like. The relative shrinkage produced by this step will result in the longitudinal pre-stressing of the flanges of the structural member.

The longitudinal hook flanges 7 by their inter-engagement with the integrated fiberglass roving, after such curing and setting, as hereinbefore described, extend deeply enough into the filler to prevent the pulling out of the flaps when the structural member is subjected to compressive forces. The aforedescribed methodalsomaterially increases the tensile strength of the structural member.

I claim:

1. In the method of making reinforced structural member comprising the steps of (a) forming the body of the structural member with at least one longitudinal recess,

(b) forming on said recess integral compressing cover walls initially open for access into said recess,

(c) filling said recess with strands of glass fiber and binder and orienting said glass fiber longitudinally in said recess,

(d) the forcing of said initially open cover walls toward one another and over said longitudinally oriented glass fiber strands, thereby to compress said strands into and against the 'walls of said recess,

(e) setting said binder thereby to integrate said glass fiber strands with the walls of said recess.

2. The method defined in claim 1 and (f) providing of said structural member with at least one longitudinal flange and forming said recess in said flange longitudinally,

3. The method defined in claim 1 and (f) providing of said structural member with at least one longitudinal flange and forming a plurality of said longitudinal recesses in said flange.

4. The method defined in claim 1 and (f) providing said structural member with longitudinal flanges along its opposite edges,- and (g) forming said recesses in each of said flanges.

" 5. The method defined in claim 1 and (f) the said forcing of said initially open cover Wall being performed by progressively rolling the cover walls'down over the fiber strands along the length of the structural member, and

(g) said setting of said binder being performed simultaneously with the gradual progressive rolling down a of the cover walls over said recess.

6. The invention defined in claim 5 and (h) said binder being heat settable polyester, heat and pressure being applied simultaneously during the progressive rolling down of said cover walls.

References Cited UNITED STATES PATENTS 3,088,561 5/1963 Ruzicka 52729 X 3,201,862 8/1965 Gotch 29470 X 2,887,762 5/1959 Dobell 29155 THOMAS H. EAGER, Primary Examiner U.S. Cl. X.R. 

